In existing technologies, there are primarily two methods for physical channel resource allocation, one is a method of localization, and the other is a method of distribution. The localization method is to divide the entire channel into several resource blocks, each of which is composed of continuous sub-carriers. The distribution method is to distribute data in each user equipment over the entire time-frequency surface.
The technology based on Orthogonal Frequency Division Multiple Access (OFDMA) is one of the major alternative schemes for future wireless communication technologies. The scheme allocates several different sub-carriers to different user equipments, and these sub-carriers are allowed to overlap in a frequency domain but always remain orthogonal to each other. A major disadvantage of the OFDMA is that it has a higher peak to average power ratio, which may cause the power amplifier efficiency to reduce significantly. In order to overcome this disadvantage and at the same time also to be able to inherit the advantages of the OFDMA, an uplink of a 3GPP Long Term Evolution (LTE) system adopts a single carrier technology, DFT-s-OFDMA technology, i.e. user data go through a DFT precoder first, and the output value transformed by the DFT is localized over the sub-carriers of the OFDMA. Although quite sensitive to frequency offset just like the OFDMA technology, the DFT-s-OFDMA technology offers a lower peak to average power ratio than the OFDMA technology and provides a pretty good result in resistance against multipath time delay.
For a certain system bandwidth, suppose that there are a total of N resource blocks and each resource block contains 12 sub-carriers, resource allocation information contains two parameters: a logical index number of a starting resource block and the number of resource blocks allocated continuously, and these two parameters are denoted by letters O and P respectively. Corresponding control signaling is required to be capable of indicating all possible (O,P) combinations.
A conventional method is to use two binary numbers to denote O and P respectively, while signaling overhead required is ceil(log2 N2). However, actually, there are only a total of
      N    ⁡          (              N        +        1            )        2possibilities for (O,P) combinations, in order to reduce the control signaling overhead, a tree-based resource allocation method is proposed, and the corresponding signaling overhead is
      ceil    (                  log        2            ⁢                        N          ·                      (                          N              +              1                        )                          2              )    .Moreover, the method provides a formula for generating the corresponding resource allocation signaling, shown as below:if (LCRBs−1)≦┌NRB/2┐, then RIV=NRB(LCRBs−1)+RBstart,else, RIV=NRB(NRB−LCRBs+1)+(NRB−1−RBstart).
Wherein, the LCRBs denotes the number of allocated continuous resource blocks P, the RBstart denotes the logical index number of the starting resource block of the allocated resources O, the NRB denotes the number of resource blocks in the current system, and the RIV denotes the decimal value of the resource allocation signaling.
When allocating 1 resource block in 5 resource blocks, there are 5 allocation cases; when allocating 2 continuous resource blocks, there are 4 allocation cases, and so forth; when allocating 5 resource blocks, there is 1 allocation case, therefore there are a total of 5+4+3+2+1=15 allocation cases, and the signaling overhead is
            ceil      (                        log          2                ⁢                              5            ⁢                          (                              5                +                1                            )                                2                    )        =    4    ,      i    .    e    .  it is necessary to use a 4-bit binary number to denote all allocation cases. However, according to the above formula, when the NRB is 5, the LCRBs is 4 and the RBstart is 1, because (4−1)=┌5/2┐, the value RIV of the resource allocation signaling calculated using the formula is 16, and it is necessary to use a 5-bit binary number to denote. But actually, there are only 15 possibilities for the denotation of the signaling, it suffices to use a 4-bit binary number to denote them all.